A carrier, for example in the case of a wheel chair, is an appliance which is indispensable for moving a lower limb handicapped person.
However, with an outdoor path on which the wheel chair travels, since in general an incline is given to the surface to drain away water etc., the following problems arise.
That is to say, when a wheel chair travels on an inclined surface of a path, then due to gravity, a centripetal acceleration occurs in the direction of the downward incline of the path. Therefore, even if a uniform force acts on the wheel chair in the left and right directions so as to move the wheel chair in a straight line, the wheel chair turns in the direction in which the centripetal acceleration occurs, so that there is a drop in the straight line travel performance of the wheel chair. In this case, a person moving the wheel chair (the lower limb handicapped person in the case where the wheel chair is moved by the strength of the handicapped person themselves, or an assistant in the case where an assistant pushes the wheel chair from behind), must obtain balance by consciously changing the force in the left and right direction with respect to the direction of travel to make the wheel chair travel in a straight line. In the case where the incline angle of the path is only slight, then straight line travel performance of the wheel chair can be maintained with this method, however when the incline angle of the path is relatively large, it is extremely difficult to obtain the left and right balance. It is also difficult to advance the wheel chair while turning the wheel chair up towards the higher level of the slope.
Furthermore, when turning the wheel chair, with a conventional wheel chair it is necessary to create an opportunity to commence turning by operating a brake on one side, so that there is also the problem that an energy loss occurs whenever turning.
The above described problems with wheel chairs similarly occur with carriers including stretchers used in hospitals etc., or wagons and the like used for example in general households or restaurants.
As a device for solving this undesirable situation with carriers, an invention related to wheel chairs has been proposed by the inventor of the present application, in Japanese Unexamined Patent Publication No. 8-182706. That is to say, a caster wheel device attached to a lower portion of a carrier body is inclined in a transverse direction with respect to the direction of travel of the carrier by means of a remotely operated inclining device. Furthermore, the straight line travel performance of the carrier is improved by offsetting the turning force due to the slope with the turning force due to incline of the caster wheel device.
However with this inclining device, the construction is such that the caster wheel device is inclined using a screw connection. Hence while the reduction ratio can be made high, there is the disadvantage that mechanical efficiency is low. Therefore, the force required for inclining the caster wheel device is large and hence operability is poor.